Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
nhan luc » nang luc
cham luc » cham soc, cham cuu, chat lua
su sach » so sach, vu sach
va vanh » va van, va danh, va hanh
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky ((nang xa) or (nang ma)) hoi. hieu va ((cham luc) OR (nhan luc)) va vanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang xa) OR (nang ma)) hoi. hieu va ((cham luc) OR (nhan luc)) va vanh dai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang xa) or (nang ma)) hoi. hieu va ((cham luc) OR (nhan luc)) va vanh dai cua tre*".